TeX source:
\begin{array}{rclcl}x^2+7x+12 &=& 0 &\vert &\text{p-q-Formel}\\x_{2,3} &=& -\dfrac{7}{2}\pm\sqrt{\left(\dfrac{7}{2}\right)^2-12} \\x_{2,3} &=& -\dfrac{7}{2}\pm\sqrt{\dfrac{1}{4}} \\\\x_2 &=& -\dfrac{7}{2}+\dfrac{1}{2} = -3 \\x_3 &=& -\dfrac{7}{2}-\dfrac{1}{2} = -4 \\\\\hspace{12em}\mathbb{L} &=& \left\{-4;-3; 2\right\}\end{array}